1. Field of the Invention
The present invention relates to a PCM digital audio signal playback apparatus for reproducing PCM (pulse code modulation) digital audio signals recorded in a recording medium, e.g. a compact disk.
2. Description of the Related Art
The recording frequencies of a digital audio signal to be recorded onto a recording medium, e.g. a compact disk (CD) or a digital audio tape (DAT), are limited by the sampling theorem to stay lower than a half the sampling frequency for avoiding any folding distortion.
In common, human ears can perceive up to 20 KHz of a single tone (pure sound) and thus, the sampling frequency is 44.1 KHz for CD recording and 48 KHz for DAT recording.
It is now acknowledged through various problems that elimination of a high-frequency component from an audio signal with a filter having a filtering characteristic of acutely blocking frequencies higher than 20 KHz, causes unfavorable results in a reproduced sound and also, such ringing effects as developed in the waveform response to a signal having high-frequency components signal such as an impulse will deteriorate the reproductivity of waveforms.